It also illegally used local contractors to carry out engineering work.

At the time union members were on strike and locked out in their battle to stop management contracting out their jobs.

In a decision released yesterday, authority member Anna Fitzgibbon said the port had made "calculated decisions" to break the law.

"Containers were stacked around the perimeter fence and the engineering workshop which obscured the vision of (union) employees on the picket line."

While on the picket line, union member Harry Mayn took photos of two men repairing port equipment.

He told the authority one of the men was an apprentice employed by POAL and the other was Andre Labus, an employee of Noell Mobile Systems, an external contractor from overseas.

The repair work would normally have been done by union members.

Other port work that would normally be done by union members was performed by another contractor, Port Star.

Port engineering manager Michael Osborne said Labus was hired before the strike to do "hands on" training, which was not work normally done by union members, and therefore was not a breach of the Employment Relations Act.

But Fitzgibbon said Labus and the apprentice did daily work normally done by union members.

She said Labus was due to travel to New Zealand to train staff but before he arrived the port was given notice of industrial action.

"It is my view that Mr Osborne, knowing there was to be a strike and that there would be no employees to train, decided to allow Mr Labus to come to New Zealand as planned."

Fitzgibbon said Osborne knew Labus would be able to perform some of the work that union members would normally do, which breached the Act.

She ordered the port to pay $30,000 to the authority and $10,000 to the union.

Maritime Union national president Garry Parsloe said the authority's decision placed POAL management in an untenable position.

"Instead of focusing on settling a fair collective agreement, the port embarked on an unprincipled plan to sack their entire stevedoring workforce and replace them with contracted labour."

Parsloe said the dispute had gone on for too long and had cost too much and he called for heads to roll at the port's management level.

"It is time for POAL to settle a fair and balanced collective agreement with us."

A port spokeswoman said the company was considering its response to the ERA ruling.

"We are disappointed with the outcome, particularly because POAL staff and management were simply focused on keeping the port running during the strikes so as to minimise the impact on the people, businesses and many other employees who rely on us.

"We are, however, pleased that during the hearing process (the Maritime Union) withdrew a number of the allegations it had initially made."